The invention relates generally to semiconductor integrated circuits, and more particularly, to an apparatus and method for positioning a spherical-shaped semiconductor integrated circuit.
Conventional integrated circuits, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
A fabrication facility is relatively expensive due to the enormous effort and expense required for creating flat silicon wafers and chips. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, facilities using in-batch manufacturing, where the wafers are processed by lots, must maintain huge inventories to efficiently utilize all the equipment of the facility. Also, because the wafers are round, and the completed chips are rectangular, accommodations must be made for the different shaped components.
A benefit of wafers is that they can be manipulated and aligned relatively easily. Wafers typically undergo a process in which a "flat" is created on one portion of its outer edge. Furthermore, processing only occurs on one side, or "face" of the wafer. The back side of the wafer, along with the wafer flat, produces an area where the wafer can be touched or handled without physical contact with other parts of the wafer and can be easily aligned. For example, the wafer can be placed on a vacuum chuck for processing. This is important because, while physical contact is required to manipulate the wafer during the many processing steps, undue contact may damage or render the wafer unusable.
Due to these and various other problems, only a few companies in the world today can successfully manufacture conventional flat chips. Furthermore, the chips must bear a high price to cover the costs of manufacturing, as well as the return on initial capital and investment.
In U.S. Pat. No. 5,955,176 filed on May 16, 1997, a method and apparatus for manufacturing spherical-shaped semiconductor integrated circuit devices is disclosed. The patent application describes several different non-contact processing techniques and requirements for manufacturing a spherical shaped device. Current methods, such as those associated with conventional wafer processing, are inadequate when called upon to handle shapes other than those resembling conventional flat wafers and chips, particularly when those shapes have curved or spherical surfaces.
For example, one difficulty associated with a spherical device is that it is difficult to align for specific processing operations. This is due primarily to how the spherical devices are processed while falling or floating through a processing tube or being held by a touchless nozzle. Also, although cameras can be used to locate alignment marks on a spherical shaped device, the alignment marks must first be in the rough vicinity of the cameras (as opposed to an opposite side of the device). Furthermore, since the device is often processed without being contacted, as opposed to the wafer on the chuck, the device's location in space is also unknown, despite the use of the alignment marks.
Therefore, what is needed is an apparatus and method for positioning and aligning such a spherical shaped device for processing operations.
Furthermore, what is needed is an apparatus and method that does not require physical contact with the spherical shaped device for positioning and aligning.